1. Field of the Invention
The present invention relates to a method for confirming ink circulation path and a method for filling with ink in an inkjet image forming apparatus in which a circulation mechanism is disposed on an ink supply flow path.
2. Description of the Related Art
In general, an inkjet image forming apparatus which forms an image by ejecting ink to a recording medium has been well known. This image forming apparatus may comprises an ink return flow path for returning the ink which has not been used for image formation as well as an ink supply flow path for supplying the ink to a recording head; and an ink circulation path for circulating the ink between an ink supply means and the recording head.
Circulating the ink in such a manner prevents the recording head in drive from increasing its temperature by utilizing a radiation effect caused by moving ink, and achieves removal of bubbles generated in the recording head and prevention of the ink from increasing its viscosity.
For instance, a technique related to initial filling to a circulation ink path, which is performed after installing the image forming apparatus, has been disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2007-007944. When initially filling the ink inside the recording head, the technique fills the ink by twice or more times and then prevents the ink from failing from the ink head and a cap covering the ink head to get a periphery dirty. Here, a sensor provided for the recording head detects whether or not the recording head has been already filled with the ink. When the sensor detects that the recording head has not been filled with the ink, a filling operation of the ink is further executed.
A technique in which heat generation from the recording head in image formation is cooled by circulating ink has been disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2006-150745. In this technique, the ink is supplied to the recording head through a buffer tank having an air buffer so that a pulse of a pump which is used for ink circulation does not affect on an ejection pressure of the recording head. In image formation, a temperature monitoring system for the recording head monitors an under-image-formation circulation flag to be raised when it is determined that the recording head should be cooled. A technique, which operates a circulation pump only when the flag is raised to circulate the ink, and as a result, the recording head is cooled to a desired temperature by means of the ink passing through the recording head, has been proposed.
In a case in which the aforementioned circulation path of the ink is configured, to detect the actual circulation of the ink even in image formation, a detection means is needed, and for example, using a flow sensor is a possible approach. To confirm at which part of the circulation path the flow of the ink has stopped, the configuration mentioned above dispersively arranges a plurality of flow amount sensors on the circulation path, and applies control (detection processing, report, etc.) to each of flow amount sensors.